package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    //封装的缓存工具类
    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {

        Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

//        //缓存穿透--返回空值方法调用
//        Shop shop = queryWithPassThrough(id);

//        //缓存击穿--互斥锁
//        Shop shop = queryWithMutex(id);

//        //缓存击穿--逻辑过期
//        Shop shop = queryWithLogicExpir(id);
//
        if(shop == null) {
            return Result.fail("店铺不存在");
        }
        return Result.ok(shop);
    }

    private static final ExecutorService CACHE_REBUILD_EXCUTOR = Executors.newFixedThreadPool(10);

    //缓存击穿--逻辑过期
    public Shop queryWithLogicExpir(Long id){
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        if(StrUtil.isBlank(shopJson)) {
            return null;
        }

        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        JSONObject data = (JSONObject) redisData.getData();
        Shop shop = JSONUtil.toBean(data, Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        if (expireTime.isAfter(LocalDateTime.now())) {
            return shop;
        }

        String lockKey = LOCK_SHOP_KEY + id;
        boolean tryLock = tryLock(lockKey);
        if(tryLock){
            CACHE_REBUILD_EXCUTOR.submit(() -> {
                try {
                 this.saveShop2Redis(id,20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    unLock(lockKey);
                }
            });
        }

        return shop;
    }

    //缓存击穿--互斥锁
    public Shop queryWithMutex(Long id){
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        if(StrUtil.isNotBlank(shopJson)) {
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        if(shopJson != null){
            return null;
        }

        String lockKey = LOCK_SHOP_KEY + id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            if(!isLock){
                Thread.sleep(20);
                return queryWithMutex(id);
            }

            shop = getById(id);
            if(shop == null) {
                stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            unLock(lockKey);
        }

        return shop;
    }

    //缓存穿透--返回空值
    public Shop queryWithPassThrough(Long id){
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        if(StrUtil.isNotBlank(shopJson)) {
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        if(shopJson != null){
            return null;
        }

        Shop shop = getById(id);
        if(shop == null) {
            stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        return shop;
    }

    private boolean tryLock(String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    private void unLock(String key) {
        stringRedisTemplate.delete(key);
    }

    public void saveShop2Redis(Long id, Long ex) {
        Shop shop = getById(id);
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(ex));
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));
    }

    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if(id == null) {
            return Result.fail("店铺id不能为空");
        }
        updateById(shop);

        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }
}
